Saturday, April 18, 2009

Now that the Maine Lighthouses map is done we're on to the Mid-Atlantic. What a job that's turning out to be! We're redoing the cartography and rewriting the text on the Hartnett House Mid-Atlantic map (newly out of stock). As with the Maine map, we're adding tower height and focal height for each lighthouse. Our researcher, Peter, has been supplying most of the stats, culled from US Coast Guard listings.

The guide that will go on the map's reverse starts with New Jersey and goes south, to Virginia. Editing was going swimmingly till I hit Concord Point Lighthouse, Havre de Grace MD. The 1827 stone tower's height was supposedly 32 ft and the focal height 36 ft.

Whoa! With a 32-ft tower, the light has to be more than 36 ft above the water. But by how much? I dash off an email to Peter and for good measure leave a voice message at the Friends of Concord Point Lighthouse.

The next day I get a call from Concord Point's president, Marsha Jacksthite. Her late mother founded the Friends some 30 years ago after thieves spirited away the light's massive Fresnel lens--without arousing the keeper in his house just 200 ft away. (Yeah, it's a fishy story.) Marsha tells me that, according to the original drawings, the tower is more like 20 ft tall. Just as important, her hometown is pronounced "Havver da Grace," not "Ahvr de Grahss" as this francophone said it.

Whew! Problem solved. Again! I change the tower height from 32 to 20.

Marsha phones back a couple of hours later. Seems that no one has actually measured the Concord Point tower in the past 180 years, so she sent someone out with a tape measure. In fact it is 29'6" tall and the lantern's midpoint another 4'10" higher. She figures that the tower sits about 4 ft above high tide, putting the light's focal point at about...39 ft.

Whew! Problem solved. Again!!! I change the tower height from 20 to 29.5.

So the Coast Guard has the wrong information about Concord Point. There are 65 more standing lighthouses in the Mid-Atlantic. Now what?

I tell myself that this is the Coast Guard's only error, make sure an errors & omissions disclaimer goes on the map's back cover and wait to hear from anyone else with a tape measure.